A conventional pillow may cause the vertebrae in the spine of a person sleeping face-down to become misaligned from their optimal positions. Misalignment of vertebrae may cause pain, damage to vertebrae, disks, muscles, and ligaments, and may limit a person's ability to move about freely. Sleeping face down on a conventional pillow may also lead to difficulty in breathing from obstruction of airflow by the pillow.
Sleeping on one's back may alleviate problems caused by twisting the neck and other parts of the spine while sleeping face down, but other breathing problems such as sleep apnea or snoring may be aggravated when a person's tongue or other soft tissues in the throat obstruct a person's airway. A person's health and well-being may depend on sleeping with the spinal column in optimal alignment and with airways unobstructed by a pillow or by the person's sleeping position.